some UI and text input thoughts

Carsten Haitzler (The Rasterman) raster at
Thu Jan 15 02:36:13 CET 2009

On Thu, 15 Jan 2009 01:19:52 +0100 Marcos Mezo <mmezo at> babbled:

> On Thursday 15 January 2009 00:42:49 Carsten Haitzler wrote:
> > On Wed, 14 Jan 2009 10:01:20 +0000 Andy Green <andy at> babbled:
> >
> > nothing to do with hardware here - all to do with software stack. the fact
> > is there is no generic "zoom" control for apps - and apps have no concept
> > of one. you also need to think about where in the stack you sit - if you go
> > to /dev/input... you will be doing your own driver work specific to 1
> > hardware type - if that changes - you are going to have to adapt. the best
> > bet is to do this higher up at the x level - but here you hit a problem.
> > mouse events ONLY go to the window they are on (or to who grabbed the
> > mouse). so in this case every app/toolkit needs to handle these themselves
> > - OR you uxe an extension like xevie and we put in an indirector for all
> > events - this indirector can/will be responsible for:
> >
> > 1. filtering (removing events, delaying and getting rid of garbage - it it
> > wants)
> > 2. selectively passing along some events and not others possibly with
> > modifications (eg translate/scale the input/output - needed for a
> > compositor if you do things like scale the window output in the compositor)
> > 3. can interpret series of events into gestures and then produce some form
> > of message (the protocol and standard are yet to be defined) that can be
> > sent to the root window o the focused window - or possibly just execute
> > some command etc. etc.
> >
> Not really knowing anything about it, but it seems to me that that's what 
> tslib is doing for right mouse button emulation.

tslib does indeed do this - but it does it at a different layer (between x and
the driver as tslib also serves as a driver emulation layer).

> Maybe somebody with the knowledge could extend tslib with some more gestures, 
> like for example the said (counter)clockwise circling that could emulate a 
> mouse wheel, which is not standard, but common for zooming in a lot of photo 
> viewers for example. It would also be useful to scroll texts,.... Or maybe 
> something like ^ for emulating the "up" key or "page-up" or....
> The problem is always that for example people drawing on the touchscreen 
> (pypennotes?) or for that matter playing with numptyphysics would not be very 
> happy :-), so if implemented it should be at least easily disabled/enabled 
> both with a gui and also with something accesible for scripts to be added on 
> application launchers.

thats why you'd want to do it above tslib - in x. at that point apps can set
hints on their windows like "do not interpret gestures" as the app may have
complex interactions and its own gesture handling in specific cases.

> Marcos
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The Rasterman (Carsten Haitzler)    raster at

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